A typical rotary packaging machine includes a clamp on the outer edge of a rotary filling table. A bag sucked by a sucking device is delivered from a bag supplying apparatus to the clamp by a delivery device and then is rotated and transported while being filled with a material to be packaged. After that, the opening of the bag is sealed to package the material. In an existing bag supplying apparatus, about 200 bags can be stocked at the same time. In the case of a packaging machine capable of packaging 50 bags per minute, an operation continues for about four minutes. This requires an operator dedicated to constantly refill bags to the bag supplying apparatus.
In Japanese Patent Laid-Open No. 2007-290768, a vertical bag-stocking mechanism is used to store a large number of bags in a standing position. The bag stocking mechanism can simultaneously stock a large number of bags with space saving and stability, reducing the number of times of refilling of bags by an operator.
FIG. 21 is a schematic diagram of a related bag supplying apparatus disclosed in Japanese Patent Laid-Open No. 2007-290768. The bag supplying apparatus includes a bag stocking mechanism 1 that stores a large number of stacked bags W and transport the bags W forward, a bag positioning mechanism 2 that transports the bags W one by one and positions the bags W at a predetermined point before the bags W are supplied to a packaging machine (not shown), bag delivery mechanisms 3 that are disposed between the bag stocking mechanism 1 and the bag positioning mechanism 2, receives the bags W one by one from the bag stocking mechanism 1, and delivers the bags W to the bag positioning mechanism 2, and a bag supplying mechanism 4 that supplies the bag W positioned at the predetermined point of the bag positioning mechanism 2 to the packaging machine.
The bag stocking mechanism 1 stores the multiple bags W placed in a standing position with the openings directed upward, transports the bags W forward, and positions the front bag W at the predetermined point on the front side of the bag stocking mechanism 1 in a transport direction. The bag stocking mechanism 1 includes a frame 6 mounted on a stand 5, a pair of right and left cassette guide members 7 mounted on the frame 6, and first conveyors 8 mounted in the frame 6.
The frame 6 includes a receiver 9 gently tilting forward and a pair of right and left side plates 11. The front and rear ends of the side plates 11 longitudinally protrudes from the receiver 9. Support shafts 15 and 16 are rotatably supported in a horizontal direction by the side plates such that pulleys 13 and 14 at the front and rear of the first conveyors 8 are fixed on the support shafts 15 and 16. A conveyor belt 17 is longitudinally looped over the pulleys 13 and 14. The upper side of the conveyor belt 17 is supported over the receiver 9. The support shafts 15 and 16 in FIG. 21 are intermittently rotated counterclockwise by a motor (not shown), allowing the conveyor belt 17 to intermittently rotate forward (to the left in FIG. 21) while sliding on the receiver 9.
The cassette guide member 7 includes a plate part 18 disposed in a vertical plane along the transport direction of the first conveyor 8 (also the transport direction of the bag W) and first stoppers 19 formed on the front end of the plate part 18 so as to be perpendicular to the transport direction. The pair of right and left cassette guide members 7 is disposed with an adjustable spacing on the receiver 9. The first stoppers 19 acting as stoppers are opposed to each other. A front bag Wa of the bags W stored in the bag stocking mechanism 1 comes into contact with the first stoppers 19 and thus is positioned thereon. The front bag Wa comes into contact with the first stoppers 19 with a predetermined width only in the vicinity of both side edges of the bag Wa.
The bag stocking mechanism 1 includes a bag supply cassette 21. The bag supply cassette 21 is substantially shape like an open box, accommodating the multiple bags W disposed in a vertical plane along the transport direction of the first conveyor 8 in a standing position with the openings directed upward. The bottom wall of the bag supply cassette 21 supports the vicinity of both bottom edges of the bags W. Both side edges of the bag W are restricted by the side walls of the bag supply cassette 21 while the bags W are transported forward by the first conveyor 8.
The bag stocking mechanism 1 further includes a bag retainer 29. The bag retainer 29 is placed on the first conveyor 8 and is moved forward with the bags w; meanwhile, the retainer 29 holds the rear ends of the multiple bags W stored in the bag supply cassette 21 so as to keep the standing position of the bags W.
The operations of the bag supplying apparatus are performed as follows:
(1) First, the bag supply cassette 21, in which the multiple bags W are stacked and stored in a standing position with the openings directed upward, is inserted between the cassette guide members 7 and is placed on the receiver 9, and then the bag retainer 29 is placed at the rear of the bag supply cassette 21.
(2) A shutter for fixing the bags W is picked up and then the first conveyor 8 is driven one time. Thus, the front bag Wa in the cassette comes into contact with the first stoppers 19 and is positioned at a pickup point. The rear ends of the bags in the cassette are held by the bag retainer 29.
(3) The bag delivery mechanisms 3 of the rotor 31 are rotated to suck and pick up the front bag Wa positioned at the pickup point. Each time the bag Wa is picked up, the first conveyor 8 is intermittently driven to transport the remaining bags accordingly in the bag supply cassette 21. In each time of pickup, the front bag Wa comes into contact with the first stoppers 19 and is positioned at the pickup point.
(4) When all the bags W in the bag supply cassette 21 are picked up, an operator detaches the bag supply cassette 21 and then sets another bag supply cassette 21 accommodating the multiple bags W (changing of cassettes), thereby refilling the bag stocking mechanism 1 with bags.
The bag stocking mechanism 1 in Japanese Patent Laid-Open No. 2007-290768 includes the bag retainer 29 that retains the rear ends of the bags in the bag supply cassette 21 and presses the bags forward in parallel while keeping the standing positions of the bags W. However, in the case of zipper bags such as a standing pack and a gusset bag that vary in thickness in a vertical direction (between the opening and bottom of the bag), a difference in thickness in the vertical direction among the bags increases with the number of bags. Thus, the bags may be curved so as to rise in an improper position in the bag stocking mechanism, causing suction holding members 32 to incorrectly suck the bags. Thus, with the related bag stocking mechanism 1, even if the bags W are placed in a standing position, this configuration limits the number of bags that can be set at the same time.
The present invention has been devised to solve the problem. An object of the present invention is to provide an apparatus for supplying a large amount of bags, the apparatus being capable of stocking a large amount of bags and allowing a packaging machine to continuously operate for a longer time than the related art.